The process for producing airtight containers, named BLOW FILL SEAL or BPS, is known, and comprises the step of forming the container (Blow), filling it (Fill) and hermetically closing it by sealing (Seal). According to this process, at first the body of the container is formed, then charged (or filled) with the desired liquid or solid filling, and then sealed.
The airtight closure (or seal: Seal step) occurs forming a cap or other closing element which is connected to the hollow body of the container and can be moved away by means of a region with a thinner section, with easy breakage.
As an example, pre-filled syringes are known, as an example like the ones described in document n. U.S. Pat. No. 5,740,931, comprising a main body, with an upper end, a neck portion integral with the main body at its upper end, a preformed closure insert which is fixed inside the neck, and an over-cap integral with the neck and removable from it.
In particular, the closure insert has a rough perimeter surface defined by axially aligned ribs uniformly spaced from one another and an axially extending passageway defined therethrough, while the overcap has a peripheral frangible web circumscribing it at the connection of the overcap with the neck portion, and it is realized so that the thermoplastic material is in intimate contact with the rough perimeter surface and wherein spaces between said ribs are filled by the thermoplastic material.
The aim of such ribs, parallel to the axis of the container, is to increase the points of contact between the hollow body and cap, blocking mutual rotation.
A kind of hermetic closure includes a cap to be applied for protecting the insert and the closing neck, so that the filling remains sterile until the moment of use, and having a breaking point defined by the notch, so as opening occurs quickly and easily. Such hermetic closure has the advantage of being easily openable by a user, so that he may access the liquid within the container. Nevertheless, said hermetic closure has the drawback of being scarcely resistant to shock during transport. Accordingly, said hermetic closure has the risk of accidental opening because of a collision, or of a sudden movement by a careless user.
Further, another drawback of said known closing system is in that it is opened without control, that is: exerting a force, in a single application, of short duration. This involves the possibility of opening the container too quickly, possibly while the container is tilted with respect to the vertical axis of the container, with the risk that the filling is released into the environment prior to its use. Furthermore, the force required for opening may vary depending on the thickness of the area to be broken.
As an alternative, it may happen that, performing a sudden movement for opening the container, the filling of the container, which had been isolated and hermetically closed just for not compromising its physical-chemical properties, could be contaminated by external agents carried by the air displacement due to said motion. In this way, the process of inserting and hermetically closing the filling within the container is useless and exceedingly laborious.
The need for a container allowing containing and preserving a substance remains, such container being easy to be opened by a user, but at the same time preserving safety in respect with the external contamination danger even at the opening moment.